Machine for cleaning covered filters.



7 PATENTED MAR. 5, 1907.

H. W. BLAISDELL. MACHINE FOR GLEANING COVERED FILTERS.

APPLICATION FILED NOV. 16, 1904.

6 SHEETS $HBET 1.

NTOH 6/1 I p MATTOHNEY WITNESSES: 4

THE NORRIS PETERS cm, WASHINGTON, o! c.

PATEN-TED MAR 5, 1907.

6 SHEETS-8HEBT 2.

H. W. BLAISDELL. MACHINE FOR OLEANING'GOVERED FILTERS.

APPLIGATION FILED NOV. 16, 1904.

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rm: NnRRls PETERS cm, WASHINGTON, n. c. v

. No. 845,746. PATENTED MAR. 5, 1907.

1-1. w. BL-AISDELL.

MACHINE FOR CLEANING COVERED FILTERS.

Arruo'nlon FILED NOV. 16, 1904.-

6 SHEETS-SHEET a.

Q MA TTOHWEK 1m: NORRIS PETERS cb.. WAsI-nNGmN. m c.

PATENTED MAR. 5,1907.

W,- BLAISDELL. MACHINE FOR CLEANING. GOVERED FILTERS.

APPLICATION FILED NOV. 16, 1904.

s -SHEETS-SHEET 4. l

/N VEN-TOH M A 770/?N Y WITNESSES rm: mamas PETERS m, muumnmn, a. c.

I A TENTED MAR. 5, 1907.

H. w. BLAI'SDELL. I MACHINE FOR CLEANING COVERED FILTERS.

APPLIOATION I ILED NOV.16, 1904.

W NVENTOH WA TTG/PNEY {HE NORRIS PETERS CO-, WASHINGTON, D. C.

I W/TNESSES:

PATENTED MAR. 5, 1907.

. H. W; BLAISDELL.

, MACHINE FOR CLEANING 00mm) FILTERS.

APPLICATION FILED NOV. 16, 1904.

BfiEBBTS-SHEBT 6.

w y T621233 1n: NORRIS PETERS co, wlsmndfon n c I-IIRAM W. BLAISDELL, OF LOS ANGELES, CALIFORNIA.

MACHINE FOR CLEANING COVERED FILTERS.

Specification of Letters Patent.

Application filed Nevembei 16, 1904.. Serial No. 233,003.

Patented March 5, 1907.

To aZZ whom it may concern.-

Be it known that l, HIRAM W. BLAISDELL, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented certain new and useful lmprovements in Machines for Cleaning Covered bilters; and 1 do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to means for operating upon or treating filtration plants or filter-beds, and particularly to machines constructed to operate upon covered filter-beds and some of the objects of the invention are to provide means of this general character simple in construction and positive and efliclent in operation.

Another object of the invention is to provide means for thoroughly cleansing the bed of a covered filter to any desired depth without removing the material of which such bed is composed and without imparting any muddiness to the fluid covering the filter.

A further object of the invention is to con struct a machine capable of operation within closed or covered filtration plants or filter: beds where the covering and the supports therefor prevent the use of machinery and necessitates the handling of the material by manual labor, as is now done at great expense of time and money.

It is also an object of this invention to provide means for operating upon the entire surface of the filter-bed and around the supports for the covering and other obstructions and to provide for the travel of such means in both directions throughout the full area of the surface to be operated upon.

Still another object of the invention is to provide means for the conveyance and discharge of the uncleaned fluid to any desired place of deposit and to accomplish this during the entire cleaning operation.

Furthermore, an object of the invention is to return a portion of the bacteria-charged wash-water to the treated surface of a filterbed, whereby a ripened filter may be formed capable of use immediately after the clearing operation shall have ceased.

With these and other objects in view the invention consists, essentially, in the construction, combination, and arrangement of parts, substantially as more fully described in the following specification and as illustrated in the accompanying drawings, folmiug part of this application, in whicl l igure 1 is a top plan view of a machine, showing the same in operative position within a covered filter-bed, the covering wltereof has been removed. big. 2 is a front elevational view of the same, showing the cleaning units or devices in their extended position. Fig. 3 is a view similar to Big. 2, partly broken away, illustrating the cleaning units or devices in their retracted position. Fig. 4 is a side elevational view of the machine. Fig. 5 is a longitudinal central sectional view of the same, and Figs. 6 and 7 illustrate details of construction.

Similar characters of reference designate corresponding parts throughout the several vlews.

This invention is particularly adapted for use with filtration plants or filter-beds which are covered or roofed over, and especially those known as slow sand filters, and before the machine is put'into operation the water upon the filter-be d to be operate d upon should preferably be drawn oil to a depth of substantially fifteen inches above the surface of the bed in order to allow sufficient head room for the operation of the macliir e.

Although this invention relates partict larl'y to use with or upon covered filter-beds, yet

it is in no manner limited or confined thereto,

and the application of this invention herein shown and described is only typical of one of the many uses of which the invention is capable.

Referring to the drawings, and particularly to the construction illustrated in Figs. 1 to 5 thereof, the reference character 1 designates the surface or filtering material of a slow sand filter-bed having a covering or roof 2, preferably of the groined arch type, supported upon columns or piers 3, provided with brackets or other devices 4, sipporting tracks or ways .5, and, if desired, addition supports 6 may be provided for the tracks st'spended from the covering or roof 2 by rods or hangers 7, all substantially as illustrated in said figthis of the drawings. A traveling supporting structtfre or frame 8 is provided with supporting wheels or rollers 9, adapted to travel on the tracks 5, so that the machine can be operated along each gallery or between each row of piers 3 to subject the entire area of filtering surface or material to treatment, as will be readily understood. Vertical transverse plates 10 and 11 are preferably secured to the bottom of the frame 8 near the forward i portion thereof, and are of sufficient width to span the distance between the piers 3, Figs. 1, 2, and 3, and supplementary or extensible plates 1.2 1.2 may be movably or slidably mounted upon or adjacent to the fixed plates 1 10 and 11, so that the former may be extended beyond the ends of the fixed plates 10 and 11 when it is desired to operate upon the surface in the plane or around the piers, substantially as shown in Fig. 2

Bearings or yokes 14, Fig. 6, are preferably slidably mounted on transverse shafts 15, desirably hollow in formation and suitably mounted in the forward portion of the frame or traveling structure 8; but in practice it will generally be found desirable to make the intermediate yoke or bearing or yokes or bearings stationary or non-slidable and leave only the outside yoke or yokes slidable or extensible, as these will afford sufficient exten sion of the machine to operate upon that portion of a filter-bed between the lines or rows of piers, substantially shown in Fig. 2. The construction of the cleaning units or devices causes the same to interlock or mesh, as shown in Fig. 3, to allow the machine to pass between the piers. The yokes 14 are preferably provided with a vertical bearing or bore 16 for operating-shafts 17,'desirably having a solid upper portion 18 and a hollow lower portion 19, and the lower portion 19 is preferably provided with ascrew-threaded connection with the hub or boss 20, having hollow raidal arms 21 communicating with the hollow portion 19 of the verticalshaft 17, desirably carrying removable tubular fingers or teeth 22, which may be provided with circumferential openings 23 to permit the discharge of the fluid therefrom, and valves or screw-threaded plugs 24 may be mounted in the radial arms 21 above the detachable fingers or teeth 22 to regulate the amount of fluid passing therethrough. Motion is preferably imparted to the cleaning devices or units just described by means of a motor 25 or other actuating apparatus, Figs. 1, 2, 3, and 4, having a sprocket-wheel 26 on the drive-shaft thereof chained to a similar wheel 27 on a worm-shaft 28, carrying a worm 29, Fig. 2, preferably in a thrustbearing 30, and said worm meshes with a worm-wheel 31, having a long hub 32, loose on the solid portion 18 of the vertical operating-shaft 17, and on the saidhub 32 is secured a pinion 33, meshing with a pinion 34, loose on an eccentric-shaft 35 and carrying a pinion 36, meshing with a gear 37, fast on the solid end of the shaft 18, and the eccentric-shaft 35 preferably provided with a handle or other devices, by means of which said shaft can be operated to throw the gears 34 and 36 out of engagement and stop the operation of the cleaning units or devices.

Adverting particularly to the construction illustrated in Figs. 1, 2, 3, 4, and 5, there is illustrated, preferably, double reels 38, desirably carrying master-gears 39, meshing with suitable idlers (not shown) driven by pinions 40 on a short shaft 41, carrying a belt-pulley 42, belted to a similar pulley 43 upon the shaft of one of the supporting-wheels 9, and the belt 44, passing over the belt-pulleys 42 and 43, is preferably provided with an adjustable take-up or other device 45,by means of which said belt canbe tightened or loosened in order to wind or stop the reels. The double reels 38 are preferably mounted on hollow separate shafts 46 and 47, the former being desirably provided with a pipe or connection 48, communicating with a centrifugal pump or other apparatus 49, operated from the shaft of a motor 49 Figs. 4 and 5,

and the pump 49 may be provided with a pipe or connection 50, connected with a lateral pipe 51, having a flexible connection 52 with a tubular extension 53, Fig. 6, of the yoke or hearing 14, and each of the reels are preferably provided with a connection 54, Fig. 5, movably attached to the hollow shaft 46 and connected with a coupling or other device 55 upon or adjacent to the circumference of the reel and constructed to removably receive one end of a flexible hose carried by the reel, on the other end whereof is preferably provided a valve or cut-off 57 and is constructed to be connected with a pipe or pipes 58, passing through the cover of the filter, substantially as illustrated in Fig. 5 of the drawings. By means of this construction the foul or waste water may be removed from the cleansing or washing chamber of the machine, the centrifugal pump withdrawing the foul fluid from the washing-chambers through the tubular extensions 53 of the yokes 14, the flexible connections 52, the lateral pipes 51, the connection 50, the pump 49, the connection 48, the hollow shaft 46, the connection 54, the hose 56, and the pipe 58, which may discharge the foul fluid at any point without the filter-b ed, and some of the bacterized water may be returned to the cleansed portion of the filter-bed through the valve-controlled connection 48 and horizontal perforated pipe or sprayer 48 in order to produce a ripened filter ready for immediate use after cleaning. It will be understood that a sufficient amount of hose will be provided to permit of the operation of the machine back and forth along each gallery and that the hose will be wound upon the reel as rapidly as the machine progresses and that the valve 57 in the end of the hose is discon-' nectible from the outlet-pipe 58. Clean water is provided for the cleaning device or units, desirably under pressure, preferably by means of loose or flexible tubing 59, having connection with any source of supply and being wound upon the reel 38, carried by the hollow shaft 47, which is provided with a ing a flexible connection 62, Figs. 5 and 6, with a tubular extension 63 of the yoke 14, communicating with the lateral ports 64 in the hollow portion 19 of the vertically-operating shaft 17,as will bereadily understood. By means of the construction just described clean fluid may be conducted, preferably under pressure, through the hose 59, the connection 60, the lateral 61, the flexible connections 62, the tubular extension 63, and the port 64 into the lower hollow portion 18 of the vertical operating-shafts 17 from whence the fluid passes into the hollow radial arms 21 and thence into the tubular fingers 22, from the orifices of which it escapes beneath the surface of the filtering material'and rises th erethrough, washing the same, while the rotation of the fingers 22 agitates the material, as will be readily understood by those skilled in the art to which this invention appertains.

In order to provide for the cleaning of the filter between the line of piers and around the same, as well as around abutments or other obstructions, the cleaning units or devices are preferably constructed to be extended and retracted, substantially as shown, respectively, in Figs. 2 and 3 of the drawings, and this is here shown as accomplished by means of hydraulic cylinder 65, Figs. 1 and 7, having fluid-ports 66 at the ends thereof communicating through pipes 66' with suitable valves (not shown) connected with the inlet and outlet pipes 61 and 51, respectively. The details of the valves and their actuating parts forming automatic trippers are no part of this invention, as they are fully described and claimed in my application, Serial No. 266,867, filed June 24, 1905. Within each cylinder is mounted a piston 67, having a rod 68 connected with the adjacent cleaning unit or device, so that when it is desired to extend or separate the cleaning units or devices fluid is admitted from inlet-pipe- 61, as described, through the proper port 66, thus forcing the piston in the desired direction to extend or separate the cleaning units or device and the extensible plates or frames 12 12, carried by the same supports, Fig. 2, and when it is desired to retract or interlock the cleaning units or devices the fluid is admitted into the cylinders 65 through the other ports 66, and the operation is reversed, as shown in Fig. 3.

To prevent the foul water from escaping from the washing-chamber, curved plates or sliding shoes 69 are preferably hinged to plates 10 and 11 adj ustably secured, Fig. 6, to or upon the front and back plates 10 and 11, so as to slide along on the surface of the fllter-bed, substantially as shown in Figs. 2, 4, and 5 of the drawings, and in order to allow the machine to approach close to the wall of the filter-bed and clean the material adjacent thereto a rope or cable 70 is preferably connected with a front shoe 69 and passes up over a sheave 71 and is attached to the inner end of a plunger or push-rod 72, so that when the latter contacts with the wall of the filter the front shoe 69 will be automatically elevated against the machine, as shown in dotted lines in Fig. 5 of the drawings. In order to partially support the machine, the

lower portion thereof is preferably inclosed to form a boat-like structure 7 3, substantially as illustrated in Figs. 4 and 5, which compartment or structure is partially submerged in the fluid covering the filter-bed during the operation of the machine.

An extension or platform 74, Figs. 1., 4, and 5, is preferably hinged to the rear of the frame 8 to be used by the person operating the machine, and when not in use the platform can be folded up against the machine, as shown in full lines in Figs. 4 and 5.

The traveling structure or frame 8 is preferably propelled at a slow speed in the forward direction and a high speed in the rearward direction, and this is desirably accomplished by means of a motor 75, having a pin ion 76, meshing with a gear-wheel 77, on the shaft of which is mounted a pinion 78, Figs. 1, 4, and 5, meshing with a large gear-wheel 79 the shaft whereof carries a .pinion 80, meshing with a second large gear-wheel 81, on the shaft 82 whereof is looosely mounted double drums or automatic clutches 83, one whereof carries a fast sprocket-wheel 84, chained to a large sprocket-wheel 85 on the propelling-shaft 86, carrying the forward supporting-wheels 9, and on said shaft is se cured a small sprocket-wheel 87, chained to a sprocket-wheel 88, fast to the other drum 83, suitable pawls or dogs being mounted upon the shaft 82, constructed to engage the peripheries of the drums 83, the one pawl engaging and driving the one drum in one direction and the other pawl engaging and driving the other drum in the other direction, as will be readily understood.

The operation of the invention will be readily understood from the foregoing description when taken in connection with the accompanying drawings and the following explanation thereof. The machine is run upon the supporting-tracks 5 of a gallery, and the hose 56 is then connected with the outlet-pipe 58 in the wall of the filter, and the hose 59 is attached to a supply connection, whereupon the motor is started, which operates the chain of gears 7 6, 7 7, 78, 79, 80, and 81, as shown in Fig. 1, thus actuating driving-shaft 82, on which gear 81 is mounted. Oneof the pawls or dogs 011 shaft 82 takes into the rim of the drum 83, carrying sprocket 84, and through its chain drives sprocket 85 on propelling-shaft 86, which latter has at its ends supporting-wheels 9. Thus the machine is advanced slowly, the

reels 38 unwind, paying out the hose 56 and 59 accordingly, the take-up being released or out or engagement with the belt 44, as w ill be understood. 'lhe cleaning units or devices are operated from the motor 25, the drive-shaft whereof carries a sprocket 26, chained to a sprocket 27 on the w orm-shaft 28, carrying a worm 29, engaging a wormwheel 31, carrying a pinion 32, meshing with a gear-w heel 34, carrying a pinion 36, engaging and driving a gear-w heel 37 on thesolid ends 18 of the vertical sha' t 17, carrying the hollow arms 21, having the depending hollow fingers 22, substantially as before described. The clean fluid passes through the hose 59, connection 60, lateral 61, flexible tube 62, passage 63, ports 64, and hollow portion 19 of the sha t 17 into the arms 21 and fingers 22, from whence the clean fluid escapes, pre-erably under pressure, to rise or percolate through the filtering material and thoroughly cleanse the same while being agitated by the revolution of the fingers. The foul or bacteria-charged fluid in the washing-chamber is draw 11 therefrom through the passage 53, flexible connection 52, lateral 51, pipe 50, centrifugal pump 49, connection 48, hollow shaft 46, tube 54, hose 56, and outlet-pipe 58, terminating outside of the filter. When the machine shall have passed beyond a set of piers or other obstructions, a suitable automatic tripper, such as described in my application Serial No. 266,867, filed June 24, 1905, permits the fluid to enter the proper port 66- of the hydraulic cylinders 65, thereby forcing the pistons 67 and pistonrods 68 away from the intermediate cleaning unit or device or forcing said parts laterally,

together with the outside cleaning units or devices, thereby extending or expanding the latter, as shown in Fig. 2. When the progress of the machine brings the same near the succeeding set of piers, the said tripper is reversed by contact therewith, and the fluid is admitted into the opposite end of the cylinders and the pistons are forced in the opposite direction, thus retracting the cleaning units or devices and the extensible plates or end of the washing-chamber, essentially as shown in Fig. 3. After the gallery shall have been traversed by the machine the motor is reversed, thus reversing the motion of shaft 82 and causing the idle dog or pawl thereon to take into the rim of the drum 83, carrying sprocket 88, which through its chain drives sprocket 87 on driving-shaft 86 in a reverse direction to that caused by sprocket and its actuating parts and at a high speed. The take-ups 44 having been put into operative position, the revolution of the rear s1; pporting-wheels 9 w ill operate the belts 43 and the sha t 40 to drive the masterwheels 39 and wind up the hose 56 and 59 upon the rub 38 as fast as the machine backs up.

It is not desired to limit or confine this invention to use in connection with closed filter-beds, as it is capable of various other applications, nor to the specific construction, 4

combination, and arrangement of parts herein shown and described, and the right is reserved to make all such changes in and modifications of the same as come within the spirit and scope of the invention.

I claim- 1. A machine constructed to operate upon covered filter-beds provided with means for cleaning the material thereof, instrumentalities for supporting the machine beneath the filter-cover and mechanism for progressing and for operating the same.

2. A machine constructed to clean covered filter-beds provided with means adapted to clean the material thereof without removing the same, instrumentalities for supporting the machine above the filter-b ed but beneath the filter-cover and mechanism for progressing and for operating the same.

3. A machine constructed to operate upon covered filterbeds provided with means for cleaning the material operated upon, means for supporting said machine above the filterbed but beneath the filter-cover, instrumentalitics for permitting the travel of the machine on said supporting means throughout the entire area of the filter-bed and mechan ism for operating the same.

4. A machine constructed to operate upon covered filter-beds provided with means for operating upon the material thereof, instrumentalities for supporting the machine, mechanism for progressing and for operating the same and means for operating on material beyond the line of progression of the machine.

5. A machine fpr cleaning covered filters provided with means for treating the material thereof, instrumentalities for'supporting the machine, mechanism for progressing and for operating the machine and devices constructed to be extended and retracted to clean the surface of the filterbed between the obstructions thereof.

6. A machine for obstructed filter-beds provided with means for operating upon the material thereof, instrumentalities whereon the machine travels, mechanism for progressmg and for operating the machine and devices constructed to be automatically extended and retracted to operate upon the surface of the filter-bed between and around obstructions.

7. A machine for cleaning obstructed filter-beds provided with operating devices, instrumentalities for effecting the travel of the machine and for operating the same and means forforcing said devices into and out of mesh to decrease and increase the area operated upon by the machine.

8. A machine for cleaning obstructed fil- IIC ter-beds provided with operating devices, instrumentalities for effecting the travel of the machine and for operating the same and means operated by the travel of the machine to retract and extend said devices to diminish and increase the area operated upon by the machine.

9. A machine for operating upon filters, havin obstructions or a covering, provided with cleaning devices, means for imparting a rotary motion thereto, instrumentalities for effecting the travel of the machine and means for automatically throwing said devices into and out of mesh to decrease or enlarge the surface operated upon by the machine.

10. A machine for obstructed or covered filters provided with cleaning devices having radial arms, means for imparting a rotary motion to said devices, mechanism for forcing said devices into and out of mesh to decrease or enlarge the area operated upon, means for supportin the machine and mechanism for effecting tile travel of the machine.

11. A machine for covered or obstructed filters provided with cleaning devices having radial arms and depending fingers, means for forcing fluid therethroug mechanism for revolving said devices, instrumentalities for effecting the travel of the machine and means for expandin or retracting said devices.

12. A machine for cleaning obstructed filter-beds provided with cleaniu devices having radial arms and depending gers, means for forcing liquid therethrough during the travel of the machine, means for projecting some of said cleaning devices beyond the line of' progression of the machine and mechanism for operating said devices. 7

13. A machine for operatin upon obstructed filter-beds provided with a plurality of cleaning devices having tubular arms car-- rying depending fingers, means for supplying fluid to said devices, means for projecting some of said cleaning devices beyond the line of progression of the machine mechanism for operating the parts and instrumentalities for Withdrawing the foul fluid.

14. A machine for operating upon obstructed filter-beds provided with cleaning devices, a double reel each portion carrying a separate hose, one set of hose being connected with said devices and with a source of supply and the other set being connected with said devices and with stationary outlet connections, whereby fluid is supplied to and drawn from said devices during the travel of the machine and means for operating the parts.

15. A machine for operating upon filterbeds provided with extensible and retractable cleaning devices, flexible connections between said devices and a source of fluid-supply outside the filter and between said devices and a stationary connection, whereby fluid is supplied to and withdrawn from said devices during the travel of the machine and mechanism for operating the parts.

16. A machine provided with cleaning devices having inlet and outlet connections, a reel carrying separate sets of flexible tubing communicating respective. y with the source of fluid-supply and with an outlet connection and with the inlet and outlet connections of said devices and means for operating the parts.

17. A machine for obstructed filters provided with guide-rods, yokes slidable thereon, cleaning devices carried by said yoke, hydraulic cylinders having pistons connected with said yokes and means for operating said pistons to separate or contract said devices and mechanism for operating the machine.

18. A machine for obstructed filters provided with guiderods, yokes slidable thereon, cleaning devices revolubly mounted in said yoke, means for expanding or contracting said devices, mechanism for rotating said device and instrumentalities for operating the machine.

19. A machine for obstructed filters provided with extensible and retractable'cleaning devices having inlet and outlet connections, laterals communicating with said connections, a flexible tubing connected with a source of fluid-supply outside the filter and with the lateral communicating with said in let connection, flexible tubing connecting with an outlet pipe or conduit, a pump in communication with the last-mentioned tubing and with the other lateral whereby the foul fluid can be drawn off from said device.

20. The combination with a covered filter having longitudinal and transverse supporting-tracks of a machine constructed to travel on said tracks, mechanism for propelling the machine, cleaning devices rotatably and slid ably mounted in the machine, means for operating saiddevices, and instrumentalities for supplying and withdrawing fluid from said devices during the operation of the machine.

21. The combination with a covered filter having longitudinal and transverse tracks of a machine having supporting-wheels con structed to travel on said tracks, reels operated from said wheels, flexible tubing thereon, cleaning devices receiving fluid through one set of said tubing and discharging fluid through the other set of the same and means for operating the parts.

22. The combination with a covered filter having supporting-tracks of a machine constructed to travel thereon provided with slidable and rotatable cleaning devices having inlet and outlet connections and carrying hollow radial arms having depending tubular fingers, a reel carrying flexible tubing connected with the source of fluid-supply and with said inlet connection, whereby fluid is supplied to said fingers, other flexible tubing upon said wheel, a pump connected with the last-mentioned tubing and with said outlet connection, devices for forcing said cleaning devices into and out of mesh and instrumentalities for operating the parts.

23. A filter-cleaning device provided with a tubular shaft having inlet-ports, a bearing for said shaft having inlet and outlet pas sages the former communicating with said ports, tubular radial arms upon said shaft and means for introducing and withdrawing the fluid through said ports.

24. A filter-cleaning device provided with i a tubular shaft having ports, a bearing for said shaft having an inlet-passage communieating with said port and having an outlet passage, induction and eduction connections respectively for said passages tubular radial arms connected with said shafts carrying tubular fingers and means for operating the parts.

25. The combination of a covered filterbed having supporting-tracks beneath the cover, of a machine constructed to travel on said tracks, means for propelling said machine, cleansing devices and means for operating said devices.

26. The combination of a covered filtercover, a cleansing device, a flexible-hose con- 1 nectlon between said devlce and a fluid-supply, a flexible hose discharge connection from said device and means for operating the parts.

27 The combination with a covered filter- \bed having supporting-tracks beneath the l cover, a cleansing device constructed to travel on said tracks, and electrical means for operating said device. l 28..The combination of a covered filterbed having su'pportingtracks beneath the l cover, a mechanism constructed to travel on i said tracks, devices for propelling the mechanism, a cleansing device, and electrical means for operating the devices. i In testimony whereof I have signed my l name to this specification, in the presence of two subscribing witnesses, at Los Angeles, in 1 the county of Los Angeles, State of California, l this 2d day of November, 1904. i HIRAM W. BLAISDELL. Witnesses: l H. T. MoRRow,

MIGNON Form. 

